Power Quality (PQ) issues are increasingly important owing to the widespread use of power electronic devices, such as switch mode power supply, Electric Vehicle (EV) charging systems, etc. Non linear devices used in EV chargers draw non sinusoidal current and distort the input current from the grid resulting in the injection of Harmonic currents. This paper considers the PQ effects of a number of types of EV charging systems, and examines the effects of multiple instances of such chargers on a simulated network. Some designs will tend to cancel certain harmonics produced by others, and others may magnify the levels of particular harmonics. In addition, the paper explores the ability of the PWM charging system to produce harmonic currents at a chosen phase angle allowing cancellation of particular harmonics.